Which age group is the most stressed-out?

I'm stressed, you're stressed, your partner is stressed, even our pets are stressed. But according a new survey from the American Psychological Association, the most stressed generation of adults in the nation is also the youngest.

So-called "Millennials," defined here as American adults ages 18 to 34, reported higher stress levels than their parents' and grandparents' generations, and more Millennials said that their stress level had increased in the last year. And 52 percent of this age group even said stress had kept them up at night.

These new figures are from the APA's annual report, Stress in America, which surveyed 2,020 American adults in a questionnaire conducted online by Harris Interactive in August 2012. The APA has commissioned the survey every year since 2007.

Generation Xers' stress level was tied with Millennials, both reporting an average level of 5.4 on a 10-point scale, but slightly fewer Gen Xers, those aged 34 to 47, said their stress increased in the past year or was causing them to lose sleep.

It doesn't take much imagination to figure out what young people might be stressing over: For one, the U.S. unemployment rate continues to creep higher, last week edging up to 7.9 percent. Some recent figures from the non-partisan group Generation Opportunity suggest the unemployment rate is even higher among 18- to 29-year-olds, at 11.5 percent, and only half of this age group believe they'll be getting Social Security.

"Most of these young people have come out of college or graduate school with horrendous student debt into a job market where there are not very many jobs," Katherine Nordal , executive director for professional practice of the APA, told "NBC Nightly News with Brian Williams." "This has put their life plans probably on hiatus; they may be postponing marriage, postponing having a family."

The APA survey found that 76 percent of Millennials surveyed by the APA say that work is a somewhat or significant stressor, compared to 65 percent of Gen Xers and 62 percent of Boomers. That's a number that has been ticking upwards -- in the APA's 2009 survey, for example, less than half of Millennials reported work as a somewhat or significant stressor.

And, as it turns out, young adults are not great at handling all this self-reported stress they're under: Forty-four percent of both Millenials and Gen Xers say they'd experienced irritability or anger due to stress, compared to 36 percent of Boomers and 15 percent of what the APA deemed "Matures," or Americans older than 67.

"Stress is a huge factor when we look at medical problems such as obesity, hypertension, diabetes, cardiac disease," says NBC's chief medical editor, Dr. Nancy Snyderman. That's more bad news for younger Americans, who say they more likely than older generations to try to manage their stress by eating junk, drinking alcohol and smoking.

It's tempting to raise an eyebrow at the findings because the stress is self-reported: How are we sure that young people are really under as much stress as they say? To a certain extent, that doesn't really matter. If you perceive yourself to be under an incredible amount of stress, then that stress is real to you, says Gail Saltz, an New York City psychiatrist and frequent TODAY contributor.

"I think that does have something to do about the acquisition of coping skills," Saltz says. "As you manage to get past things, your ability to look back as something else comes along and say, 'Well, I got through that' -- that goes a long way."

We do seem to get better at managing stress as we age, according to the APA's self-reported figures. While 29 percent of Millennials, 35 percent of Gen Xers and 38 percent of Boomers (adults aged 48 to 66) said they are doing an excellent or very good job at managing stress, half of those older than 67 thought they were doing a bang-up job of keeping their stress manageable.